Generally, corrugated cardboard, produced by attaching liner sheets to both sides of a corrugated sheet using an adhesive to thus increase cushioning ability, is mainly used in the manufacture of product-packaging boxes. However, because a packaging box made of conventional corrugated cardboard plays only a simple role in preventing damage to products stored in the box due to the cushioning ability of the corrugated cardboard, it is difficult to use it to maintain the freshness of various natural food products stored in the box, including agricultural products, livestock products, marine products and forest products, for a long period of time, or to absorb and eliminate pungent odors emitted by the products. Further, these days, agricultural chemicals are used in large amounts to kill harmful insects or remove weeds in the course of cultivation of agricultural products, and thus agricultural chemical components may remain on the crops, undesirably negatively affecting human bodies. Accordingly, there is urgently required a packaging box that is able to naturally neutralize and remove remaining toxic agricultural chemical components when agricultural products are packaged in boxes.
In this regard, there have been proposed methods of manufacturing a functional corrugated cardboard box by adding sticky starch with zeolite powder, having microscopic holes 1 nm or less in size and serving as an adsorbent, an ion exchanger, and a dehydrating agent.
However, in the adhesive for functional corrugated cardboard according to such a conventional technique, as seen in FIG. 1, the particle size of zeolite powder 110 is larger than that of starch 120, and thus the zeolite powder 110 is easily separated in the course of usage. The zeolite powder 110, which is separated from the adhesive, is not harmful to the human body, but feels dirty to consumers.
In order to solve this problem, attempts to control the particle size of the zeolite powder 110 so that it is the same as that of the starch 120 have been devised. In this case, however, the zeolite powder 110 is completely enclosed with the starch 120, thereby closing the microscopic holes in zeolite, making it impossible to exhibit high absorption capability and anion exchange capability. Accordingly, the functions of the adhesive for neutralizing and removing remaining toxic agricultural chemical components or efficiently discharging such components are drastically decreased.